It is known that the purpose of such a device, for example of the TANS (“Terrain Avoidance and Warning System”) type or of the GPWS (“Ground Proximity Warning System”) type is to detect any risk of collision of the aircraft with the surrounding terrain and to warn the crew when such a risk is detected, such that the latter can then implement a terrain avoidance maneuver. Such a device generally comprises:                a first means knowing a profile of the terrain located in front of the aircraft;        a second means for determining the effective values of particular flight parameters;        a third means for calculating, from said effective values, an avoidance path that is the best possible representation of the real situation, and for checking if this avoidance path is compatible with said profile of the terrain, at least over a predetermined distance in front of the aircraft; and        a fourth means for transmitting a corresponding warning signal, if said third means detects an incompatibility.        
In general, said third means uses a model, intended to represent an avoidance maneuver carried out by an aircraft, for calculating the corresponding path. However, the model used which generally takes account of a constant load factor and a fixed path representative of a stabilized state of the aircraft, reproduces fairly well the maneuver implemented by the aircraft. Furthermore, the approximations made make it necessary to take account of large error margins, in order not to overestimate the real performance of the aircraft during an avoidance maneuver. However, the taking into account of the error margins can in particular result in false alarms. The calculation mode and the checking mode used by said third means are not therefore completely reliable.